Unit 1 - Key Area 2

Question 1

Competition between individuals belonging to two or more different species who have very similar resource requirements which are in short supply.

Answer 1

Interspecific competition

Question 2

A stable plant community which is maintained by persistent human interference, such as burning and grazing

Answer 2

Plagioclimax

Question 3

An animal that must meet its energy requirements by ingesting other organisms or organic matter derived originally from plants. Also known as a consumer

Answer 3

Heterotroph

Question 4

Interactions between organisms which reduce the population when numbers are high and allow the population to increase when numbers are low.

(factors include disease, predation, competition)

Answer 4

Density dependent

Question 5

Succession that occurs on a pre-existing soil after primary succession has been disrupted or destroyed and the ecological community has been disturbed

Answer 5

Secondary succession

Question 6

Population overshoot

Answer 6

A temporary situation that occurs when a population exceeds its carrying capacity, before lack of resources causes a population crash.

Question 7

An animal that relies on external environments for temperature control instead of generating their own body heat.

Answer 7

Ectotherm

Question 8

Net primary productivity (NPP)

Answer 8

The rate at which an ecosystem accumulates energy or biomass, excluding the energy used for the process of respiration.

NPP = GPP – respiration

Question 9

The series of changes in an ecosystem when one community is replaced by another community as a result of changes in biotic and abiotic factors.

Answer 9

Succession

Question 10

Predator–prey cycle

Answer 10

As a population of one species increases, its predator populations will increase in response. As the prey numbers fall due to predation, the predator numbers will also fall due to reducing resource availability.

Question 11

What does this graph show?

Answer 11

A J-curve population

• lag phase
• exponential growth
  e. g. human population growth

Question 12

A sudden decline in the numbers of individual members in a population, species or group of organisms, usually in response to scarcity of resources, intra-specific competition and/or other biotic factors

Answer 12

Population crash

Question 13

The assimilation of food into new biomass through the transfer of organic material between trophic levels.

Answer 13

Secondary productivity

Question 14

An animal that obtains its energy by consuming both plant and animal material

Answer 14

Omnivore

Question 15

Any organism that gains its energy from other organisms. Also known as a heterotroph

Answer 15

Consumer

Question 16

A relationship between species that helps to prevent overpopulation of a particular species to ensure the survival of the species as a whole

Answer 16

Interdependence

Question 17

A level or position in a food chain, occupied by a group of organisms that have a similar feeding mode, ie autotrophs and heterotrophs (herbivores, carnivores, omnivores).

Answer 17

Trophic level

Question 18

The stages of succession in an ecosystem advancing towards its climax community.

Answer 18

Seral stage

Examples of seres include xerosere, hydrosere, psammosere

Question 19

What does this show?

Answer 19

S-curve population growth

• lag time
• exponential growth
• carrying capacity reached

Question 20

The rate at which autotrophs (producers) produce a total biomass in a given area and time period.

Answer 20

Gross primary productivity (GPP)

Question 21

Endotherm

Answer 21

An animal that uses internally generated heat to maintain body temperature independent of external temperature change.

Question 22

The maximum population size of a species that the environment can sustain indefinitely.

Answer 22

Carrying Capacity

Question 23

Density independent factor

Answer 23

Factors, usually natural disasters, which reduce the reproduction rate or increase the death rate of organisms independently of population density. (wild fires / droughts)

Question 24

The percentage of biomass produced by one trophic level that is transferred and incorporated into biomass at the next trophic level.

Answer 24

Ecological efficiency

Question 25

A measure of the rate at which new organic matter develops through photosynthesis

Answer 25

Primary productivity

Question 26

An interaction that occurs between organisms whenever there is shared demand for a limited resource.

Answer 26

Competition

Question 27

Climax communty

Answer 27

The final stage of succession, in which a community of plants and animals remains stable and exists in balance with each other and their environment.

Question 28

The colonisation of a new site by communities of plants and animals after an event has removed all existing soil, for example glaciation or a lava flow. This type of succession must first wait for soil to develop sufficiently to support colonising species.

Answer 28

Primary succession

Question 29

Intra-specific competition

Answer 29

Competition between individuals of the same species for the same limited resource

Question 30

Parasitism

Answer 30

A symbiotic relationship between organisms of different species in which the host is a source of food and a habitat for the parasite.

+/-

Question 31

Autotroph

Answer 31

An organism that can produce its own food; usually a green plant that produces its own food via photosynthesis, through the conversion of light energy into chemical energy. Also known as a producer